body, ul, p {
    padding: 0;
    margin: 0;
}

header {
    height: 80px;
    text-align: center;
    border-bottom: 2px dotted #000;
}

.left {
    height: 80px;
    padding: 20px;
    line-height: 40px;
    font-size: 28px;
    color: rgb(19, 150, 255);
    font-weight: 700;
}

ul {
    width: 100%;
    height: 60px;
    display: flex;
}

li {
    flex: 1;
    list-style: none;
    height: 60px;
    /*background: pink;*/
    float: left;
    border: 1px solid #ccc;
}

nav a {
    display: block;
    text-decoration: none;
    width: 100%;
    height: 60px;
    line-height: 60px;
    text-align: center;
    color: black;
}

.active {
    background: rgb(70,174,247);
}

nav {
    margin-bottom: 30px;
}